1. Field of the Invention
This invention relates generally to forming indicia on work pieces and, more particularly, to a method and apparatus for permanently code marking container components, whether the container body or a closure therefor.
2. Description of the Prior Art
It is desirable to provide code marking on products to identify, for example, the date of manufacture, lot number, plant, and the like so that when production problems are detected the source of the problem may be more easily detected and necessary corrections made. Moreover, if the product is utilized to contain food, beverage or other items which may be subject to deterioration with the passage of time, and if the container is manufactured on the same day as it is filled with such items, then marking may be used to indicate a date by which contained item must be used.
A number of methods have been used in the past for code marking products including various types of date and other indicia stamping with ink. However, ink is not a satisfactory solution when the product has subsequent handling, washing or other process steps that may remove all or part of the indicia. Further, contact between an ink indicia and items contained by the product may not be desirable from a health standpoint.
As an alternative, such indicia have been permanently impressed on a product being manufactured. This approach has been used in die and mold forming processes by cutting on the die elements or in the mold cavities the indicia to be inscribed on the product. However, if the code marks or indicia need to be changed frequently, as in a date of manufacturing coding, then it requires shutting down production equipment for extended periods with an attendant loss of production and increase in labor costs. Moreover, such mold and die elements may then have to be discarded or reworked to provide a new set of desired indicia.